Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
2.1.4.9.2 Field of application
Hardening is applied in the processing of edible oils for the production of margarine and other
edible fats.
2.1.4.9.3 Description of techniques, methods and equipment
Hardening, or hydrogenation of oils, is the process of saturating mono or poly-unsaturated fatty
acids by adding hydrogen gas (H2) for the hydrogenation and nickel as a catalyst. Hydrogen
molecules, in the presence of nickel and under special process conditions, saturate the
unsaturated bonds of the fatty acids of edible oils. Neutral or bleached oil is heated to a
temperature of 150 to 205 °C in the presence of a nickel catalyst, maximum 10 kg catalyst/tonne
product. H2 is then added to the mixing reactor to achieve the hardening, i.e. the transformation
from oil to fat. Hydrogenation is an exothermic process. After the reaction, the fats are separated
from the nickel, using filter presses or other filter systems. In a minority of cases, the nickel
catalyst can be re-used several times until it is deactivated. Specialised companies recycle the
spent nickel. The residual nickel concentration in the fats is removed by bleaching, which
produces bleaching earth contaminated with nickel. The equipment used for hardening consists
of mixing vessels, reaction tanks, autoclaves and filters.
2.1.4.10 Sulphitation (D.10)
2.1.4.10.1 Objective
The aim of sulphitation is to prevent either microbiological degradation, unwanted colour
formation or to adjust pH.
2.1.4.10.2 Field of application
Sulphitation is applied in winemaking, potato processing and shellfish processing. It is also
sometimes applied in sugar production to adjust the pH.
2.1.4.10.3 Description of techniques, methods and equipment
Sulphitation is the introduction of sulphur dioxide (SO2) into liquids; the quantity of SO2 which
can be added is regulated. It can be introduced in various forms. First, in gaseous form,
generated either by burning sulphur or from liquefied gas and direct expansion. The SO2 is
drawn by a fan into an absorption column in which the liquid flows. Second, in liquid form,
from liquefied gas or in sodium or potassium bisulphite solution. The SO2 may also be stored as
a liquid, under approximately 5 bar, in horizontal cylindrical tanks of 25 to 50 m 3 capacity, from
which it can then be introduced into the desired process stream. Third, in solid form, as sodium
or potassium metabisulphite dissolved in the liquid to be treated.
An alternative sulphite source is ammonium bisulphite. Sodium bisulphite can also be used.
2.1.4.11 Carbonatation (D.11)
2.1.4.11.1 Objective
The aim of carbonatation is to remove impurities from a solution.
2.1.4.11.2 Field of application
Applied in the sugar industry.
32 January 2006 RHC/EIPPCB/FDM_BREF_FINAL